This invention relates generally to the field of catalysis, and more particularly relates to novel complexes of mid-transition metals and unsaturated nitrogenous ligands that are useful, inter alia, as polymerization catalysts. The invention additionally relates to methods for using the novel compounds as catalysts, particularly in the preparation of polymers such as polyolefins.
Many processes and catalysts are known for the preparation of homopolymeric or copolymeric olefins and other polymers. Ziegler-Natta catalyst compositions, developed in the 1950s, were found to be particularly useful in the preparation of polyolefins. These catalyst compositions comprise transition metal compounds such as titanium tetrachloride and an alkylaluminum (e.g., triethylaluminum) cocatalyst. The systems were found to be advantageous because of their high activity, and were largely consumed during polymerization.
Subsequent catalyst systems have been designed to provide more control over polymer structure and properties than could be achieved with Ziegler-Natta catalysts. These later catalysts have well-defined active sites and can be rationally designed to produce a specific polymer product, i.e., having predetermined structure and properties. Such catalysts include, for example, metal complexes known as xe2x80x9cmetallocenes.xe2x80x9d The term xe2x80x9cmetallocenexe2x80x9d was initially coined in the early 1950s to refer to dicyclopentadienyliron, or xe2x80x9cferrocene,xe2x80x9d a structure in which an iron atom is contained between and associated with two parallel cyclopentadienyl groups. The term is now used to refer generally to organometallic complexes in which a metal atom (not necessarily iron) is coordinated to at least one cyclopentadienyl ring ligand. A. D. Horton, xe2x80x9cMetallocene Catalysis: Polymers by Design,xe2x80x9d Trends Polym. Sci. 2(5):158-166 (1994), provides an overview of metallocene catalysts and their advantages, and focuses on now-conventional complexes of Group IV transition metal complexes and cyclopentadienyl ligands (Cp2MX2, wherein Cp represents a cyclopentadienyl ligand, M is Zr, Hf or Ti, and X is Cl or CH3). Unfortunately, however, although metallocenes do provide significant advantages relative to the traditional Ziegler-Natta catalysts, the high cost and difficulties associated with heterogenization of metallocenes, as well as the oxophilic nature of the early transition metals, have limited the applicability of metallocenes as commercial polymerization catalysts.
Because polyolefins such as polyethylene and polypropylene are such important commercial polymers, there is an ongoing need for improved polymerization techniques and polymerization catalysts. Recently, researchers have developed new catalysts suitable for olefin polymerization that are complexes of late transition metals and substituted diimine ligands. Such catalysts are described, for example, in Bres et al., PCT Publication No. WO 98/49208, published Nov. 5, 1998. Other similar catalysts, comprised of diimine ligands and selected metals, are described in Bennett, PCT Publication No. WO 98/27174, published Jun. 25, 1998, and in Brookhart et al., PCT Publication No. WO 98/30612, published Jul. 16, 1998. While these catalysts have some advantages, they are lacking in several significant respects. Perhaps most importantly, the aforementioned catalysts are incapable of producing commodity polymers such as linear low density polyethylene (xe2x80x9cLLDPE,xe2x80x9d having a density of about 0.918 to 0.935 g/cm3) and isotactic polypropylene (xe2x80x9ciPPxe2x80x9d).
The present invention is thus addressed to the aforementioned need in the art, and provides novel compounds useful as polymerization catalysts, e.g., in the polymerization of olefins. The catalysts provide for numerous advantages relative to the polymerization catalysts of the prior art, in that they:
(1) are simple and cost-effective to synthesize;
(2) allow for exceptional control over the structure and properties of the polymeric product;
(3) are highly active polymerization catalysts;
(4) can be used in stereospecific polymerization to provide stereoregular polymers, including isotactic and syndiotactic polymers;
(5) enable preparation of commodity polymers such as linear low density polyethylene and isotactic polypropylene;
(6) can be used as either supported or homogeneous polymerization catalysts;
(7) are quite versatile and can be used in conjunction with a variety of monomer types; and
(8) can be used to catalyze reactions other than polymerization reactions, e.g., hydrogenation.
The invention thus represents a significant advance in the field of catalysis, as prior to the development of the catalysts disclosed and claimed herein, only a few of the aforementioned advantages could be achieved with a single catalyst system.
Accordingly, it is a primary object of the invention to provide novel compounds useful as catalysts, particularly as polymerization catalysts.
It is another object of the invention to provide such compounds which are complexes of a mid-transition metal and at least one unsaturated nitrogenous ligand.
It is yet another object of the invention to provide such compounds containing two unsaturated nitrogenous ligands that are asymmetrically substituted, such that the compounds are useful as stereospecific catalysts.
It is still another object of the invention to provide such catalysts which are isospecific, thus enabling preparation of isotactic polymers.
It is another object of the invention to provide such catalysts which are syndiospecific, thus enabling preparation of syndiotactic polymers.
It is a further object of the invention to provide such compounds which are useful for preparing polyolefins or other polymers deriving from the polymerization of addition polymerizable monomers containing one or more degrees of unsaturation.
It is still a further object of the invention to provide catalyst systems containing a compound of the invention, a catalyst activator such as a metal alkyl, hydride, alkylhydride, alkylhalide or the like, and, optionally, additives such as inert diluents (e.g., a volatile hydrocarbon) and polymerization rate accelerators (e.g., Lewis bases, including amines and anilines).
It is yet a further object of the invention to provide a method for using the novel catalysts to prepare polyolefins or other polymers deriving from the polymerization of addition polymerizable monomers containing one or more degrees of unsaturation.
It is an additional object of the invention to provide a method for using the novel catalysts to prepare stereoregular polymers such as isotactic polypropylene.
It is still an additional object of the invention to provide a method for using the novel catalysts to prepare linear low density polyethylene.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention.
In one embodiment, the novel compounds have the structure L1[MQ1Q2]L2 in which M is a mid-transition metal, Q1 and Q2 are each a univalent radical, and L1 and L2 are ligands, wherein each of L1 and L2 contains a first coordinating atom that is a nitrogen atom contained within a Cxe2x95x90N group, and a second coordinating atom that is either a second nitrogen atom, which may or may not be present in a second Cxe2x95x90N group, or an oxygen, sulfur or phosphorus atom. Each Cxe2x95x90N group may be a true imine functionality contained within an acyclic molecular segment, or may represent a linkage within a heterocycle such as a pyridine or pyrimidine ring. In this embodiment, the mid-transition metal M is selected from the group consisting of Nb, Ta, Mo, W, Mn and Re, and L1 and L2 may be covalently linked to each other, but typically represent separate and distinct ligands. Additionally, L1 and L2 may be the same or different. When a stereospecific catalyst is desired, L1 and L2 are substituted accordingly. That is, for an isospecific catalyst, the two ligands L1 and L2 are each asymmetrically substituted. For example, with a diimine ligand, one of the two imine nitrogens will be bound to a relatively small substituent, providing little or no steric bulk, while the other of the two imine nitrogens will be bound to a relatively large substituent, providing significant steric bulk, and the isospecific catalysts herein will contain two such ligands. For a syndiospecific catalyst, the two ligands L1 and L2 will differ substantially in size. Again, using diimine ligands for purposes of illustration, the imine nitrogen atoms of L1 will typically be substituted with smaller substituents, while the imine nitrogen atoms of L2 will typically be substituted with bulkier substituents. As will be appreciated by those skilled in the art, the stereoregularity of a polymer is an important aspect of molecular structure because it is a primary determinant of crystallinity. High stereoregular polymers typically have high crystallinity, while a nonstereoregular polymer is often amorphous (or of low crystallinity). Crystallinity, in turn, is a prime determinant of key physical properties such as stiffness, solvent resistance, and melting temperature. Thus, the fact that the present catalysts may be designed as stereospecific catalysts, useful in preparing polymers having predetermined stereoregularity, is a significant advantage of the invention.
The novel compounds may be positively charged, in which case they will be associated with a negatively charged counterion. Such complexes may be represented as [L1(MQ1Q2)L2]+yxc2x7y/z[Axe2x88x92z] wherein y and z are generally in the range of 1 to 4, more typically are 1 or 2, and A is any anion, e.g., halide, pseudohalide, or the like. It is to be understood that any compounds of the invention that are represented or drawn in neutral form, without any ionic charge indicated (e.g., as xe2x80x9cL1[MQ1Q2]L2xe2x80x9d), are also intended to encompass positively charged such compounds associated with an anion.
In another embodiment, the novel compounds are complexes having the structure L1[MQ1Q2]LALB as shown in formula (I) 
wherein:
M is a mid-transition metal, i.e., a metal selected from Groups VA, VIA and VIIA of the periodic table of the elements;
Q1 and Q2 are independently selected from the group consisting of hydrido, halide, alkoxy, amido, unsubstituted C1-C30 hydrocarbyl, C1-C30 hydrocarbyl substituted with one or more substituents such as electron-withdrawing groups, and C1-C30 hydrocarbyl-substituted Group IVB elements, or Q1 and Q2 may together form an alkylidene olefin, acetylene, or a five- or six-membered cyclic hydrocarbyl group;
m and n are independently zero or 1;
q is an optional double bond;
X is N, O, S or P, with the provisos that (a) when X is N or P, then either n is 1 or q is present as a double bond, but not both, and (b) when X is O or S, then n is zero and q is absent;
R1, R6, and R7 are independently hydrido, hydrocarbyl or substituted hydrocarbyl, and R2 and R5 are independently hydrido, halo, hydrocarbyl or substituted hydrocarbyl, or R1 and R2 and/or R5 and R6 may be taken together to form a linkage xe2x80x94Qxe2x80x94, resulting in a five- or six-membered ring, wherein Q is xe2x80x94[(CR)a(Z)b]xe2x80x94 in which a is 2, 3 or 4, Z is N, O or S, b is zero or 1, the sum of a and b is 3 or 4, and R is selected from the group consisting of hydrido, halo, hydrocarbyl, hydrocarbyloxy, trialkylsilyl, NR82, OR9, and NO2, wherein R8 and R9 are each independently hydrocarbyl, or wherein R moieties on adjacent carbon atoms may be linked to form an additional five- or six-membered ring, or R2 and R5 may together form a linkage xe2x80x94Qxe2x80x94 as just defined;
R3 and R4 are independently selected from the group consisting of hydrido and hydrocarbyl, or at least one of R3 and R4 may be bound through a lower alkylene linkage to an atom contained within LA or LB;
LA and LB are ligands which may be the same or different and are independently selected from the group consisting of nitrogen-containing, sulfur-containing and oxygen-containing heterocycles, tertiary amines and phosphines, or LA and LB may together form a single bidentate such as ligand L2 where L2 is as defined previously, and wherein L2 may or may not be the same as L1,
with the proviso that when (a) LA and LB form L2, (b) L2 is identical to L1, and (c) M is V or Cr, then either (d) R1and R2 or R5 and R6 are taken together to form a linkage Q as defined above, or (e) X is other than N, or both (d) and (e).
When LA and LB together form a single bidentate ligand L2, preferred complexes have the formula (II) 
wherein:
M is a mid-transition metal, i.e., metal selected from Groups VA, VIA and VIIA of the periodic table;
Q1 and Q2 are as defined for structural formula (I); and
qa, ma, na, R1a, R2a, R3a, R4a, R5a, R6a and R7a are defined as for q, m, n, R1, R2, R3, R4, R5, R6 and R7, respectively.
In a related embodiment, novel compounds are provided having the structure of formula (III) 
wherein i and j are independently zero, 1, 2 or 3, R10, R11, R12 and R13 are independent hydrocarbyl or substituted hydrocarbyl, and M, Q1, Q2, LA and LB are as defined previously, or LA and LB together represent an additional L3 moiety.
In a further embodiment, complexes having the structure of formula (IV) are provided 
wherein:
M is a mid-transition metal selected from Groups VA, VIA and VIIA of the periodic table of the elements;
Q1 and Q2 are as defined above for structural formulae (I) and (II);
R14 is hydrocarbyl or substituted hydrocarbyl, and R15 is hydrido, hydrocarbyl or substituted hydrocarbyl, or R14 and R15 taken together form a ring;
R14a is hydrocarbyl or substituted hydrocarbyl, and R15a is hydrido, hydrocarbyl or substituted hydrocarbyl, or R14a and R15a taken together form a ring;
R16 is hydrocarbyl or substituted hydrocarbyl, and R17 is hydrido, hydrocarbyl or substituted hydrocarbyl, or R16 and R17 taken together form a ring;
R16a is hydrocarbyl or substituted hydrocarbyl, and R17a is hydrido, hydrocarbyl or substituted hydrocarbyl, or R16a and R17a taken together form a ring;
R18, R18a, R19 and R19a are independently selected from the group consisting of hydrido and hydrocarbyl, or one of R18 and R18a may be bound to one of R19 and R19a through a lower alkylene linkage; and
m and ma are independently zero or 1.
The compounds of the invention, as alluded to above, may be positively charged and thus associated with a negatively charged counterion. That is, a metal complex of formulae (I), (II), (III) or (IV) may carry a positive charge +y, where y is an integer in the range of 1 through 4, more typically 1 or 2, and is associated with y/z anions each bearing a negative charge xe2x88x92z.
In an additional embodiment of the invention, a catalyst system is provided comprised of (1) a compound of the invention, as a catalyst, and (2) a catalyst activator such as a metal alkyl, hydride, alkylhydride, alkylhalide or the like, effective to convert the catalyst to a catalytically active ionic species. An exemplary catalyst is activator is methyl aluminoxane (xe2x80x9cMAOxe2x80x9d). Generally, the catalyst system will also contain an inert diluent, e.g., a hydrocarbon solvent, and optional additives such as polymerization rate accelerators. In catalyzing reactions, e.g., polymerization reactions, hydrogenation reactions, and the like, the compounds of the invention are used in such a catalyst system. Typically, polymerization involves conventional processes wherein selected monomers are contacted with a compound of the invention under reaction conditions effective to provide the desired polymer composition or other product.
In addition to their utility as polymerization catalysts, the novel compounds are also useful in catalyzing other types of reactions, e.g., hydrogenation, dehydrocoupling, cyclization, substitution, carbomagnesation and hydrosilylation.
Definitions and Nomenclature
Before the present compounds, compositions and methods are disclosed and described, it is to be understood that unless otherwise indicated this invention is not limited to specific molecular structures, ligands, or the like, as such may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.
It must be noted that, as used in the specification and the appended claims, the singular forms xe2x80x9ca,xe2x80x9d xe2x80x9canxe2x80x9d and xe2x80x9cthexe2x80x9d include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to xe2x80x9ca substituentxe2x80x9d includes one or more substituents, reference to xe2x80x9ca ligandxe2x80x9d includes one or more ligands, and the like.
The term xe2x80x9calkylxe2x80x9d as used herein refers to a branched or unbranched saturated hydrocarbon group of 1 to approximately 24 carbon atoms, typically 1 to approximately 12 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, octyl, decyl, tetradecyl, hexadecyl, eicosyl, tetracosyl and the like, as well as cycloalkyl groups such as cyclopentyl, cyclohexyl and the like. The term xe2x80x9clower alkylxe2x80x9d intends an alkyl group of 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms.
The term xe2x80x9calkylenexe2x80x9d as used herein refers to a difunctional saturated branched or unbranched hydrocarbon chain containing from 1 to approximately 24 carbon atoms, typically 1 to approximately 12 carbon atoms, and includes, for example, methylene (xe2x80x94CH2xe2x80x94), ethylene (xe2x80x94CH2xe2x80x94CH2xe2x80x94), propylene (xe2x80x94CH2xe2x80x94CH2xe2x80x94CH2xe2x80x94), 2-methylpropylene (xe2x80x94CH2xe2x80x94CH(CH3)xe2x80x94CH2xe2x80x94), hexylene (xe2x80x94(CH2)6xe2x80x94), and the like. xe2x80x9cLower alkylenexe2x80x9d refers to an alkylene group of 1 to 6, more preferably 1 to 4, carbon atoms.
The term xe2x80x9calkenylxe2x80x9d as used herein refers to a branched or unbranched hydrocarbon group of 2 to approximately 24 carbon atoms, typically 2 to approximately 12 carbon atoms, containing at least one carbon-carbon double bond, such as ethenyl, n-propenyl, isopropenyl, n-butenyl, isobutenyl, t-butenyl, octenyl, decenyl, tetradecenyl, hexadecenyl, eicosenyl, tetracosenyl and the like. Preferred alkenyl groups herein contain 2 to 12 carbon atoms and 2 to 3 carbon-carbon double bonds. The term xe2x80x9clower alkenylxe2x80x9d intends an alkenyl group of 2 to 6 carbon atoms, preferably 2 to 4 carbon atoms, containing one xe2x80x94Cxe2x95x90Cxe2x80x94 bond. The term xe2x80x9ccycloalkenylxe2x80x9d intends a cyclic alkenyl group of 3 to 8, preferably 5 or 6, carbon atoms.
The term xe2x80x9calkenylenexe2x80x9d refers to a difunctional branched or unbranched hydrocarbon chain containing from 2 to approximately 24 carbon atoms, typically 2 to approximately 12 carbon atoms, and at least one carbon-carbon double bond. xe2x80x9cLower alkenylenexe2x80x9d refers to an alkenylene group of 2 to 6, more preferably 2 to 5, carbon atoms, containing one xe2x80x94Cxe2x95x90Cxe2x80x94 bond.
The term xe2x80x9calkynylxe2x80x9d as used herein refers to a branched or unbranched hydrocarbon group of 2 to approximately 24 carbon atoms, as above containing at least one xe2x80x94Cxe2x89xa1Cxe2x80x94 bond, such as ethynyl, n-propynyl, isopropynyl, n-butynyl, isobutynyl, t-butynyl, octynyl, decynyl and the like. Preferred alkynyl groups herein contain 2 to 12 carbon atoms. The term xe2x80x9clower alkynylxe2x80x9d intends an alkynyl group of 2 to 6, preferably 2 to 4, carbon atoms, and one xe2x80x94Cxe2x89xa1Cxe2x80x94 bond.
The term xe2x80x9calkynylenexe2x80x9d refers to a difunctional branched or unbranched hydrocarbon chain containing from 2 to approximately 24 carbon atoms as before and at least one carbon-carbon triple bond. xe2x80x9cLower alkynylenexe2x80x9d refers to an alkynylene group of 2 to 6, more preferably 2 to 5, carbon atoms, containing one xe2x80x94Cxe2x89xa1Cxe2x80x94 bond.
The term xe2x80x9calkoxyxe2x80x9d as used herein intends an alkyl group bound through a single, terminal ether linkage; that is, an xe2x80x9calkoxyxe2x80x9d group may be defined as xe2x80x94OR where R is alkyl as defined above. A xe2x80x9clower alkoxyxe2x80x9d group intends an alkoxy group containing one to six, more preferably one to four, carbon atoms.
The term xe2x80x9carylxe2x80x9d as used herein refers to an aromatic species containing 1 to 5 aromatic rings, either fused or linked, and either unsubstituted or substituted with 1 or more substituents typically selected from the group consisting of xe2x80x94(CH2)xxe2x80x94NH2, xe2x80x94(CH2)xxe2x80x94COOH, xe2x80x94NO2, halogen, alkyl, alkenyl, alkynyl, alkoxy, alkenyloxy, alkynyloxy, alkylthio, aryl, aralkyl, and the like, where x is an integer in the range of 0 to 6 inclusive as outlined above. Preferred aryl substituents contain 1 to 3 fused aromatic rings, and particularly preferred aryl substituents contain 1 aromatic ring or 2 fused aromatic rings. The terms xe2x80x9caralkylxe2x80x9d and xe2x80x9calkarylxe2x80x9d refer to moieties containing both alkyl and aryl species, typically containing less than about 24 carbon atoms, and more typically less than about 12 carbon atoms in the alkyl segment of the moiety, and typically containing 1 to 5 aromatic rings. The term xe2x80x9caralkylxe2x80x9d refers to aryl-substituted alkyl groups, while the term xe2x80x9calkarylxe2x80x9d refers to alkyl-substituted aryl groups. The terms xe2x80x9caralkylenexe2x80x9d and xe2x80x9calkarylenexe2x80x9d are used in a similar manner to refer to aryl-substituted alkylene and alkyl-substituted arylene moieties.
The term xe2x80x9carylenexe2x80x9d refers to a difunctional aromatic moiety; xe2x80x9cmonocyclic arylenexe2x80x9d refers to a cyclopentylene or phenylene group. These groups may be substituted with up to four ring substituents as outlined above.
The term xe2x80x9cheterocyclicxe2x80x9d refers to a five- or six-membered monocyclic structure or to an eight- to eleven-membered bicyclic structure which is either saturated or unsaturated. Each heterocycle consists of carbon atoms and from one to four heteroatoms selected from the group consisting of nitrogen, oxygen and sulfur. As used herein, the terms xe2x80x9cnitrogen heteroatomsxe2x80x9d and xe2x80x9csulfur heteroatomsxe2x80x9d include any oxidized form of nitrogen and sulfur, and the quaternized form of any basic nitrogen. Examples of heterocyclic groups include piperidinyl, pyrazinyl, morpholinyl and pyrrolidinyl.
xe2x80x9cHaloxe2x80x9d or xe2x80x9chalogenxe2x80x9d refers to fluoro, chloro, bromo or iodo, and usually relates to halo substitution for a hydrogen atom in an organic compound. Of the halos, chloro and fluoro are generally preferred.
xe2x80x9cHydrocarbylxe2x80x9d refers to univalent unsubstituted and substituted hydrocarbyl radicals containing 1 to about 30 carbon atoms, typically 1 to about 24 carbon atoms, preferably 1 to about 12 carbon atoms, including branched or unbranched, saturated or unsaturated species, such as alkyl groups, alkenyl groups, aryl groups, heteroaryl groups, and the like. The term xe2x80x9clower hydrocarbylxe2x80x9d intends a hydrocarbyl group of one to six carbon atoms, preferably one to four carbon atoms. The term xe2x80x9chydrocarbylenexe2x80x9d intends a divalent unsubstituted or unsubstituted hydrocarbyl moiety, including branched or unbranched, saturated or unsaturated species, or the like. The term xe2x80x9clower hydrocarbylenexe2x80x9d intends a hydrocarbylene group of 1 to 6 carbon atoms, preferably 1 to 4 four carbon atoms. The term xe2x80x9chydrocarbyloxyxe2x80x9d or xe2x80x9chydrocarbylthioxe2x80x9d refer to a hydrocarbyl group bound through a terminal ether or thio linkage.
By xe2x80x9csubstitutedxe2x80x9d as in xe2x80x9csubstituted hydrocarbylxe2x80x9d or xe2x80x9csubstituted hydrocarbylenexe2x80x9d is meant that the hydrocarbyl or hydrocarbylene group contains one or more substituent groups which are inert under the process conditions to which the compound containing these groups is subjected. The substituent group may replace a hydrogen atom or may be found as a linkage within the carbon chain. xe2x80x9cMonosubstitutedxe2x80x9d refers to a hydrocarbyl or hydrocarbylene group having one substituent group and xe2x80x9cdisubstitutedxe2x80x9d refers to a hydrocarbyl or hydrocarbylene group containing two substituted groups. The substituent groups also do not substantially interfere with the process. Included in the meaning of xe2x80x9csubstitutedxe2x80x9d are heteroaromatic rings. Examples of substituents include, but are not limited to, amino (including primary amino and alkyl-substituted, typically lower alkyl-substituted, secondary and tertiary amino), alkyl (typically lower alkyl), alkoxy (typically lower alkoxy), alkenyl (typically lower alkenyl), aryl (e.g., phenyl), halo, haloalkyl, imino, nitro, and the like; xe2x80x9csubstitutedxe2x80x9d also refers to the replacement of a carbon atom in a hydrocarbyl or hydrocarbylene group with a non-hydrocarbyl linkage such as xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94NHxe2x80x94, xe2x80x94N(alkyl)xe2x80x94, etc.
The term xe2x80x9cunsaturated nitrogenous compoundxe2x80x9d refers to a compound having a Cxe2x95x90N moiety. Unsaturated nitrogenous compounds herein include both a true imine wherein the Cxe2x95x90N moiety is present in an acyclic molecular segment, as well as nitrogenous heterocycles in which the carbon-nitrogen bond is present in an aromatic ring, e.g., as in pyridine, pyrimidine, pyrazine, and the like.
Unless otherwise indicated, the term xe2x80x9cmid-transition metalxe2x80x9d refers to any metal selected from Groups VA, VIA and VIIA of the periodic table (using the IUPAC system for naming chemical elements). Exemplary mid-transition metals include, but are not limited to, Mb, Ta, Mo, W, Mn, Re, V and Cr.
xe2x80x9cOptionalxe2x80x9d or xe2x80x9coptionallyxe2x80x9d means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not. For example, the phrase xe2x80x9coptionally substituted hydrocarbylxe2x80x9d means that a hydrocarbyl moiety may or may not be substituted and that the description includes both unsubstituted hydrocarbyl and hydrocarbyl where there is substitution.
A xe2x80x9cheterogeneousxe2x80x9d catalyst as used herein refers to a catalyst which is supported on a carrier, typically although not necessarily a substrate comprised of an inorganic, solid, particulate porous material such as silicon and/or aluminum oxide.
A xe2x80x9chomogeneousxe2x80x9d catalyst as used herein refers to a catalyst which is not supported but is simply admixed with the initial monomeric components in a suitable solvent.
The term xe2x80x9cstereoregularityxe2x80x9d is used in the conventional sense to refer to the relative positioning of substituent groups of monomer units in a polymer chain. The term xe2x80x9cstereostructurexe2x80x9d refers to the stereoregularity of any particular polymer. Possible polymeric stereostructures include the following: atactic polymers, in which the arrangement of substituents is random; isotactic polymers, in which all substituents are identically oriented; syndiotactic polymers, in which the orientation of substituents alternates; stereoblock polymers, containing blocks of monomers all oriented the same way, and blocks of monomers all oriented the opposite way; isoblock polymers, containing blocks of isotactic monomer units separated by a single oppositely oriented monomer unit; hemiisotactic polymers, having every other monomer unit oriented in the same way (isotactic), separated by a monomer that is randomly oriented; and hemisyndiotactic polymers having every other monomer unit oriented in the opposite way (syndiotactic), separated by a randomly oriented monomer unit.
By xe2x80x9cstereospecificxe2x80x9d is meant a catalyst that will provide a polymer of predetermined, desired stereoregularity. The preferred catalysts herein are xe2x80x9cstereospecific.xe2x80x9d By xe2x80x9cisospecificxe2x80x9d is meant a catalyst that will provide an isotactic polymer. By xe2x80x9csyndiospecificxe2x80x9d is meant a catalyst that will provide a syndiospecific polymer. The most preferred catalysts herein are xe2x80x9cisospecificxe2x80x9d and xe2x80x9csyndiospecific.xe2x80x9d
As used herein all reference to the Periodic Table of the Elements and groups thereof is to the version of the table published by the Handbook of Chemistry and Physics, CRC Press, 1995, which uses the IUPAC system for naming groups.
The Novel Compounds
In a first embodiment, then, the compounds of the invention are organometallic complexes represented by the formula L1[MQ1Q2]L2 in which M is a mid-transition metal, Q1 and Q2 are each a univalent radical, and L1 and L2 are ligands, wherein each of L1 and L2 is an unsaturated nitrogenous ligand. L1 and L2 may identical, or they may be different; in addition, they may represent separate and distinct ligands, or they may be covalently linked to each other.
In this embodiment, the mid-transition metal xe2x80x9cMxe2x80x9d is selected from the group consisting of Mb, Ta, Mo, W, Mn and Re.
Q1 and Q2 are each a univalent radical, and are preferably independently selected from the group consisting of hydrido, halide, alkoxy, amido, and substituted or unsubstituted C1-C30 hydrocarbyl; if substituted, the substituents are typically although not necessarily electron-withdrawing groups such as a halogen atom, an alkoxy group, or the like, or the substituents may be Group IVB elements. Alternatively, Q1 and Q2 may together form an alkylidene olefin (i.e., xe2x95x90CR2 wherein R is hydrogen or hydrocarbyl, typically lower alkyl), acetylene, or a five- or six-membered cyclic hydrocarbyl group. Preferred Q1 and Q2 moieties are hydrido, amido, C1-C12 alkyl, and C1-C12 alkyl substituted with one or more halogen and/or alkoxy groups, typically one to six such groups, and C1-C12 alkyl substituted with a Group IVB element. Particularly preferred Q1 and Q2 moieties are hydrido, amido, lower alkyl and lower alkoxy.
L1 and L2 are unsaturated nitrogenous ligands. More particularly, each of L1 and L2 contains a first coordinating atom that is a nitrogen atom contained within a Cxe2x95x90N group, and a second coordinating atom that is either a second nitrogen atom, which may or may not be present in a second Cxe2x95x90N group, or an oxygen, sulfur or phosphorus atom. Each Cxe2x95x90N group may be a true imine functionality contained within an acyclic molecular segment, or may represent a linkage within a heterocycle such as a pyridine or pyrimidine ring.
In another embodiment, the novel compounds are complexes having the structure L1[MQ1Q2]LALB as shown in formula (I) 
wherein the various substituents are defined as follows.
M is a mid-transition metal, i.e., a metal selected from Groups VA, VIA and VIIA of the periodic table of the elements. Preferred mid-transition metals in this embodiment are Mb, Ta, Mo, W, Mn, Re, V and Cr.
Q1 and Q2 are each univalent radicals, as defined earlier herein.
The subscripts m and n are independently zero or 1, preferably are both zero, and letter xe2x80x9cqxe2x80x9d represents an optional double bond.
X is N, O, S or P, with the provisos that (a) when X is N or P, then either n is 1 or q is present as a double bond, but not both, and (b) when X is O or S, then n is zero and q is absent.
R1, R6 and R7 are independently hydrido, hydrocarbyl or substituted hydrocarbyl, as defined above, and R2 and R5 are independently hydrido, halo, hydrocarbyl or substituted hydrocarbyl, also as defined above, or R1 and R2 and/or R5 and R6 may be taken together to form a linkage xe2x80x94Qxe2x80x94, resulting in a five- or six-membered cyclic group. Similarly, R2 and R5 may together form a linkage xe2x80x94Qxe2x80x94. As explained above, Q is xe2x80x94[(CR)a(Z)b]xe2x80x94 in which a is 2, 3 or 4, Z is N, O or S, b is zero or 1, the sum of a and b is 3 or 4, and R is selected from the group consisting of hydrido, halo, hydrocarbyl, hydrocarbyloxy, trialkylsilyl, NR82, OR9, and NO2, wherein R8 or R9 are each independently hydrocarbyl, or wherein R moieties on adjacent carbon atoms may be linked to form an additional five- or six-membered ring.
Examples of R1, R6 and R7 thus include, but are not limited to, hydrido, methyl, ethyl, n-propyl, isopropyl, methoxy, ethoxy, isopropoxy, phenyl, benzyl, phenoxy, pyridyl, diisopropylphenyl, methoxyphenyl, trimethylsilyl, triethylsilyl, and the like; R2 and R5 substituents can include any of the foregoing as well as halogen substituents, i.e., chloro, fluoro, bromo and iodo, with chloro and fluoro preferred. When R1 and R2 and/or R5 and R6 are linked, the cyclic structures so formed may be alicyclic or aromatic, including, for example, furanyl, pyrrolyl, thiophenyl, imidazolyl, pyrazolyl, oxathiolyl, pyridinyl, methylpyridinyl, ethylpyridinyl, pyridazinyl, pyrimidinyl, pyrazinyl, piperidinyl, piperazinyl, morpholinyl, tetrahydrothiophenyl, tetrahydrofuranyl, tetrahydropyranyl, 1,4-dioxanyl, etc. When R2 and R5 are linked, the resulting structures are alicyclic and may or may not contain heteroatoms; such moieties include, for example, cyclopentane, cyclohexane, tetrahydrofuran, tetrahydropyran, tetrahydrothiophene, 1,4-dioxane, 1,2-dithiole, 1,3-dithiole, piperazine, morpholine, and the like.
R3 and R4 are independently selected from the group consisting of hydrido and hydrocarbyl, preferably hydrido or lower alkyl, or at least one of R3 and R4 may be bound through a lower alkylene linkage, preferably a methylene linkage, to an atom contained within LA or LB.
LA and LB are ligands which may be the same or different and are generally selected from: nitrogen-containing heterocycles such as pyridine, pyridazine, pyrimidine, pyrazine, 1,3,5-triazine, 1,2,4-triazine, 1,2,3-triazine, pyrrole, 2H-pyrrole, 3H-pyrrole, pyrazole, 2H-imidazole, 1,2,3-triazole, 1,2,4-triazole, indole, 3H-indole, 1H-isoindole, cyclopenta(b)pyridine, indazole, quinoline, isoquinoline, cinnoline, quinazoline, naphthyridine, piperidine, piperazine, pyrrolidine, pyrazolidine, quinuclidine and imidazolidine; sulfur-containing heterocycles such as thiophene, 1,2-dithiole, 1,3-dithiole, thiepin, benzo(b)thiophene and benzo(c)thiophene; oxygen-containing heterocycles such as 2H-pyran, 4H-pyran, 2-pyrone, 4-pyrone, 1,2-dioxin, 1,3-dioxin, oxepin, furan, 2H-1-benzopyran, coumarin, chroman-4-one, isochromen-1-one, isochromen-3-one, xanthene, tetrahydrofuran and 1,4-dioxan; mixed heterocycles such as isoxazole, oxazole, thiazole, isothiazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole, 1,3,4-oxadiazole, 1,2,3,4-oxatriazole, 1,2,3,5-oxatriazole, 3H-1,2,3-dioxazole, 3H-1,2-oxathiole, 1,3-oxathiole, 4H-1,2-oxazine, 2H-1,3-oxazine, 1,4-oxazine, 1,2,5-oxathiazine, o-isooxazine, pyrano[3,4-b]pyrrole, indoxazine, benzoxazole, anthranil and morpholine; tertiary amines, particularly trialkylamines, and preferably tri(lower alkyl)amines such as triethylamine, methyldiethylamine, trimethylamine, methyldiisopropylamine, and the like; phosphines, particularly trialkylphosphines, and preferably tri(lower alkyl)phosphines such as triethylphosphine, methyldiethylphosphine, trimethylphosphine, methyldiisopropylphosphine, and the like. Alternatively, LA and LB may together form a single bidentate ligand such as L2 or L3 where L2 and L3 are as defined previously, and wherein the ligand may or may not be the same as L1, with the proviso that when (a) LA and LB form L2, (b) L2 is identical to L1, and (c) M is V or Cr, then either (d) R1 and R2 or R5 and R6 are taken together to form a linkage xe2x80x94Qxe2x80x94 as defined above, or (e) X is other than N, or both (d) and (e).
The complex may be electronically neutral, or it may be charged, depending on the selected metal and its oxidation state. That is, compounds of the invention may also be represented as [L1(MQ1Q2)L2]+yxc2x7y/z[Axe2x88x92z] wherein y and z are generally in the range of 1 to 4, more typically are 1 or 2, and A is any anion. A may be, for example, a halide or pseudohalide ion, or a fluorohydrocarbylborate such as tetra(pentafluorophenyl)borate, sodium tetrakis[(bis-3,5-trifluoromethyl)phenyl]borate, H+(OCH2CH3)2[(bis-3,5-trifluoromethyl)phenyl]borate, trityltetra(pentafluorophenyl)borate and tris(pentafluorophenyl)boron.
When LA and LB together form a single bidentate ligand L2, preferred such structures have the formula (II) 
wherein
M, Q1 and Q2 are as defined above with respect to the structure of formula (I), and
qa, ma, na, R1a, R2a, R3a, R4a, R5a, R6a and R7aare defined as q, m, n, R1, R2, R3, R4, R5, R6 and R7, respectively. The ligands L1 and L2 may be the same or different, and they are optionally linked, either directly or indirectly, through one or more covalent bonds. For example, one of R3 and R3amay be bound to one of R4 and R4a through a lower alkylene linkage, preferably a methylene linkage.
Again, compounds of formula (II) may be electronically neutral or they may be positively charged and associated with a negatively charged anion, as explained above.
An example a preferred type of catalyst encompassed by structural formula (II) is shown in formula (V), as follows: 
wherein M, Q1, Q2, R5, R5a, R6 and R6a are as defined above with respect to the structures of formulae (I), (II), (III) and (IV), and R20, R20a, R21, R21a, R22 , R22a, R23 and R23a are preferably hydrido or hydrocarbyl of 1 to 10 carbon atoms, or any two adjacent R20, R20a, R21, R21a, R22, R22a, R23 and R23a groups may be linked to form a further ring or rings, for example a benzene ring. Specific examples of R20, R20a, R21, R21a, R22, R22a, R23 and R23a include, but are not limited to, methyl, ethyl, n-propyl, n-butyl, n-hexyl and n-octyl, although most preferably, R20, R20a, R21, R21a, R22, R22a, R23 and R23a are all hydrogen.
An example of a particularly preferred catalyst encompassed by structural formula (V) is shown in formula (VI), as follows: 
wherein M, Q1, Q2, R20 and R20a are as defined above with respect to the structure of formula (V); optimally, in structure (VI), R20 and R20a are both hydrido. This catalyst is representative of those catalysts of the invention that are isospecific, insofar as each ligand is asymmetrically substituted, having a bulky molecular segment appended to one of the nitrogen atoms, and a smaller molecular segment appended to the second of the nitrogen atoms.
Another example of stereospecific catalyst encompassed by structural formula (II) is shown in formula (VII), as follows. 
This catalyst is representative of those catalysts of the invention that are generally syndiospecific, insofar as one ligand is substituted with bulky (2,4-diisopropylphenyl) substituents, while the other ligand is substituted with far smaller (methyl) substituents.
Asymmetric substitution and its correlation to stereospecificity, and particularly isospecificity and syndiospecificity, may be illustrated as follows: 
In structure (VIII), Rs represents a relatively small substituent, while RL represents a relatively large, sterically bulky substituent. Such a catalyst is xe2x80x9cisospecificxe2x80x9d and may be used to prepare isotactic polyolefins, e.g., isotactic polypropylene, which has far more commercial value than atactic polypropylene. 
In contrast to the atactic polymer, isotactic polypropylene is a high melting, strong, crystalline polymer, useful in a variety of industrial contexts, e.g., as a plastic, as a fiber, and the like. The stereospecific catalysts of the invention can also be used to provide other isotactic polymers, including isotactic poly(1-butene) and poly(4-methyl-1-pentene). 
is generally syndiospecific, insofar as one ligand contains two sterically bulky xe2x80x9cRLxe2x80x9d substituents, and the other ligand contains two relatively small xe2x80x9cRSxe2x80x9d substituents. The relative steric bulk of RL and RS provides for a syndiospecific catalyst, which can be used in stereospecific polymerization to prepare syndiotactic polymers such as syndiotactic polypropylene. 
It should be emphasized that any of the foregoing metal complexes may be either electronically neutral or positively charged, wherein, in the latter case, the complex will be associated with a negatively charged counterion.
The catalysts of the invention are also useful to prepare linear low density polyethylene, a preferred type of polyethylene for many commercial uses, wherein the polymer contains up to about 10% of a comonomer such as 1-butene, 1-hexene, 1-octene or 4-methyl-1-pentene.
Specific catalysts encompassed by formula (I) include, but are not limited to, the following: 
In a related embodiment, novel compounds are provided having the structure of formula (III) 
wherein i and j are independently zero, 1, 2 or 3, R10, R11, R12 and R13 are independently hydrocarbyl or substituted hydrocarbyl, and M, Q1, Q2, LA and LB are as defined previously, or LA and LB together represent an additional L3 moiety.
Other complexes suitable as catalysts herein have the structure of formula (IV) 
wherein:
M is a mid-transition metal, and Q1 and Q2 are as defined above for structural formula
R14 is hydrocarbyl or substituted hydrocarbyl, and R15 is hydrido, hydrocarbyl or substituted hydrocarbyl, or R14 and R15 taken together form a ring;
R14a is hydrocarbyl or substituted hydrocarbyl, and R15a is hydrido, hydrocarbyl or substituted hydrocarbyl, or R14a and R15a taken together form a ring;
R 16 is hydrocarbyl or substituted hydrocarbyl, and R17 is hydrido, hydrocarbyl or substituted hydrocarbyl, or R16 and R17 taken together form a ring;
R16a is hydrocarbyl or substituted hydrocarbyl, and R17a is hydrido, hydrocarbyl or substituted hydrocarbyl, or R16a and R17a taken together form a ring;
R 18, R 18a, R19 and R19a are independently selected from the group consisting of hydrido to and hydrocarbyl, or one of R18 and R18a may be bound to one of R19 and R19a through a lower alkylene linkage; and
m and ma are independently zero or 1.
Synthesis
The complexes of the invention are synthesized using any one of several techniques. In general, the complexes may be prepared using relatively simple and straightforward synthetic processes known to those skilled in the art and/or described in the pertinent texts and literature. In general, the novel complexes are prepared by first providing an unsaturated nitrogenous compound such as an imine-containing ligand to serve as xe2x80x9cL1,xe2x80x9d which can be obtained commercially or readily synthesized using techniques known to those skilled in the art of synthetic chemistry and/or are described in the pertinent literature. See, e.g., PCT Publication Nos. WO 98/27124, WO 98/30612 and WO 98/49208, and U.S. Pat. No. 5,866,663, all cited earlier herein. For example, a diimine ligand having the structural formula 
wherein R and Rxe2x80x2 are defined as any of R1, R2, R5 and R6, defined earlier herein with respect to compounds of formula (I), may be synthesized by addition of the primary amine Rxe2x80x94NH2 to the diketone 
in a simple, straightforward, one-step reaction.
Other ligands containing one or more Cxe2x95x90N groups may be synthesized in a similar manner, by reaction of a suitable primary amine with a selected aldehyde or a ketone. For example, the asymmetric ligand 
may be readily synthesized from 2,6-diisopropylaniline and 2-pyrazinecarboxaldehyde, as described, for example, in Weidenbruch et al. (1993) Organometallic Chemistry 454:3 5. Reference may also be had to Patai, The Chemistry of the Carbon-Nitrogen Double Bond (1970), which provides information on various synthetic methods that can be used in the preparation of imines.
The metal complexes are then synthesized using a metallation reaction in which at least one equivalent of the selected ligand or ligands are caused to react with a metal compound MQ1Q2Y2 wherein M is a mid-transition metal, i.e., a Group VA, Group VIA or Group VIIA metal, Q1 and Q2 are as defined earlier herein, and the Y substituents are xe2x80x9cleaving groupsxe2x80x9d that are generally selected from the group consisting of halide, pseudohalide (e.g., lower alkoxy such as methoxy), flurohydrocarbylborates, etc. During the metallation reaction, then, the Y groups are eliminated. Alternative metallation techniques are also possible, as will be appreciated by those skilled in the art. A suitable metallation reaction is described in Example 1, part (b). Other suitable metallation reactions for preparing the present compounds will be known to those skilled in the art and/or described in or readily derived from the pertinent texts and literature.
Preparation of the Catalyst System
The novel compounds of the invention, when used as polymerization catalysts, are used in conjunction with a conventional catalyst activator as will be appreciated by those skilled in the art. Thus, prior to use, the compounds of the invention are incorporated into a catalyst system which includes such an activator. Suitable catalyst activators include metal alkyls, hydrides, alkylhydrides, and alkylhalides, such as alkyllithium compounds, dialkylzinc compounds, trialkyl boron compounds, trialkylaluminum compounds, alkylaluminum halides and hydrides, and tetraalkylgermanium compounds. Specific examples of useful activators include n-butyllithium, diethylzinc, di-n-propylzinc, triethylboron, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, ethylaluminum dichloride, dibromide and dihydride, isobutyl aluminum dichloride, dibromide and dihydride, di-n-propylaluminum chloride, bromide and hydride, diisobutyl-aluminum chloride, bromide and hydride, ethylaluminum sesquichloride, methyl aluminoxane (xe2x80x9cMAOxe2x80x9d), hexaisobutyl aluminoxane, tetraisobutyl aluminoxane, polymethyl aluminoxane, tri-n-octylaluminum, tetramethyl germanium, and the like. Other activators which are typically referred to as ionic cocatalysts may also be used; such compounds include, for example, (C6H6)3+, C6H5xe2x80x94NH2CH3+, and fluorohydrocarbylboron compounds such as tetra(pentafluorophenyl)borate, sodium tetrakis[(bis-3,5-trifluoromethyl)phenyl]borate, H+(OCH2CH3)2[(bis-3,5-trifluoromethyl)phenyl]borate, trityltetra(pentafluorophenyl)borate and tris(pentafluorophenyl)boron. Mixtures of activators may, if desired, be used. Generally, the catalyst activator is such that upon combination with a compound of the invention, a catalytically active ionic species results, i.e., the catalyst activator Z ionically associates with the catalyst L1[MQ1Q2]L2 to produce the catalytically active ionic species (L1[M+Q1Q2]L2)Zxe2x88x92.
For liquid phase or slurry polymerization, the catalyst and activator are generally mixed in the presence of inert diluents such as, for example, aliphatic or aromatic hydrocarbons, e.g., liquified ethane, propane, butane, isobutane, n-butane, n-hexane, isooctane, cyclohexane, methylcyclohexane, cyclopentane, methylcyclopentane, cycloheptane, methylcycloheptane, benzene, ethylbenzene, toluene, xylene, kerosene, Isopar(copyright) M, Isopar(copyright) E, and mixtures thereof. Liquid olefins or the like which serve as the monomers or comonomers in the polymerization process may also serve as the diluent; such olefins include, for example, ethylene, propylene, butene, 1-hexene and the like. The amount of catalyst in the diluent will generally be in the range of about 0.01 to 1.0 mmoles/liter, with activator added such that the ratio of catalyst to activator is in the range of from about 10:1 to 1:2000, preferably in the range of from about 1 :1 to about 1:200, on a molar basis.
Preparation of the catalyst/activator/diluent mixture is normally carried out under anhydrous conditions in the absence of oxygen, at temperatures in the range of from about xe2x88x9290xc2x0 C. to about 300xc2x0 C., preferably in the range of from about xe2x88x9210xc2x0 C. to about 200xc2x0 C.
The catalyst, activator and diluent are added to a suitable reaction vessel, in any order, although, as noted above, the catalyst and activator are usually mixed in the diluent and the mixture thus prepared then added to the reactor.
Use in Polymerization
The novel catalysts are used to prepare polymeric compositions using conventional polymerization techniques known to those skilled in the art and/or described in the pertinent literature. The monomer(s), catalyst and catalyst activator are contacted at a suitable temperature at reduced, elevated or atmospheric pressure, under an inert atmosphere, for a time effective to produce the desired polymer composition. The catalyst may be used as is or supported on a suitable support. In one embodiment, the novel catalysts are used as homogeneous catalysts, i.e., as unsupported catalysts, in a gas phase or liquid phase polymerization process. A solvent may, if desired, be employed. The reaction may be conducted under solution or slurry conditions, in a suspension using a perfluorinated hydrocarbon or similar liquid, in the gas phase, or in a solid phase powder polymerization.
Liquid phase polymerization generally involves contacting the monomer or monomers with the catalyst/activator mixture in the polymerization diluent, and allowing reaction to occur under polymerization conditions, i.e., for a time and at a temperature sufficient to produce the desired polymer product. Polymerization may be conducted under an inert atmosphere such as nitrogen, argon, or the like, or may be conducted under vacuum. Preferably, polymerization is conducted in an atmosphere wherein the partial pressure of reacting monomer is maximized. Liquid phase polymerization may be carried out at reduced, elevated or atmospheric pressures. In the absence of added solvent, i.e., when the olefinic monomer serves as the diluent, elevated pressures are preferred. Typically, high pressure polymerization in the absence of solvent is carried out at temperatures in the range of about 180xc2x0 C. to about 300xc2x0 C., preferably in the range of about 250xc2x0 C. to about 270xc2x0 C., and at pressures on the order of 200 to 20,000 atm, typically in the range of about 1000 to 3000 atm. When solvent is added, polymerization is generally conducted at temperatures in the range of about 150xc2x0 C. to about 300xc2x0 C., preferably in the range of about 220xc2x0 C. to about 250xc2x0 C., and at pressures on the order of 10 to 2000 atm.
Polymerization may also take place in the gas phase, e.g., in a fluidized or stirred bed reactor, using temperatures in the range of approximately 60xc2x0 C. to 120xc2x0 C. and pressures in the range of approximately 10 to 1000 atm.
The monomer or comonomers used are addition polymerizable monomers containing one or more degrees of unsaturation. Olefinic or vinyl monomers are preferred, and particularly preferred monomers are xcex1-olefins having from about 2 to about 20 carbon atoms, such as, for example, linear or branched olefins including ethylene, propylene, 1-butene, 3-methyl-1-butene, 1,3-butadiene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 4-methyl-1-hexene, 1,4-hexadiene, 1,5-hexadiene, 1-octene, 1,6-octadiene, 1-nonene, 1-decene, 1,4-dodecadiene, 1-hexadecene, 1-octadecene, and mixtures thereof. Cyclic olefins and diolefins may also be used; such compounds include, for example, cyclopentene, 3-vinylcyclohexene, norbornene, 5-vinyl-2-norbornene, 5-ethylidene-2-norbornene, dicyclopentadiene, 4-vinylbenzocyclobutane, tetracyclododecene, dimethano-octahydronaphthalene, and 7-octenyl-9-borabicyclo-(3,3,1)nonane. Aromatic monomers which may be polymerized using the novel metallocenes include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-tert-butylstyrene, m-chlorostyrene, p-chlorostyrene, p-fluorostyrene, indene, 4-vinylbiphenyl, acenaphthalene, vinylfluorene, vinylanthracene, vinylphenanthrene, vinylpyrene and vinylchrisene. Other monomers which may be polymerized using the present catalysts include methylmethacrylate, ethylacrylate, vinyl silane, phenyl silane, trimethylallyl silane, acrylonitrile, maleimide, vinyl chloride, vinylidene chloride, tetrafluoroethylene, isobutylene, carbon monoxide, acrylic acid, 2-ethylhexylacrylate, methacrylonitrile and methacrylic acid.
In gas and slurry phase polymerizations, the catalyst is used in a heterogeneous process, i.e., supported on an inert inorganic substrate. Conventional materials can be used for the support, and are typically particulate, porous materials; examples include oxides of silicon and aluminum, or halides of magnesium and aluminum. Particularly preferred supports from a commercial standpoint are silicon dioxide and magnesium dichloride.
The polymeric product resulting from the aforementioned reaction may be recovered by filtration or other suitable techniques. If desired, additives and adjuvants may be incorporated into the polymer composition prior to, during, or following polymerization; such compounds include, for example, pigments, antioxidants, lubricants and plasticizers.
The compounds of the invention are also useful in catalyzing other types of reactions, i.e., reactions other than polymerizations. Such reactions include, but are not limited to, hydrogenation, dehydrocoupling, cyclization, substitution, carbomagnesation and hydrosilylation. Methods for using the metal complexes of the invention to catalyze the aforementioned reactions and others will be known to those skilled in the art and/or described in the pertinent texts and literature.
It is to be understood that while the invention has been described in conjunction with the preferred specific embodiments thereof, that the foregoing description as well as the examples which follow are intended to illustrate and not limit the scope of the invention. Other aspects, advantages and modifications within the scope of the invention will be apparent to those skilled in the art to which the invention pertains.
All patents, patent applications, and publications mentioned herein are hereby incorporated by reference in their entireties.
Experimental
The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how to prepare and use the catalysts of the invention. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.) but some errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, temperature is in xc2x0 C. and pressure is at or near atmospheric.
All patents, patent applications, journal articles and other references mentioned herein are incorporated by reference in their entireties.
Examples 1 through 4 describe methods for synthesizing various complexes of the invention; Example 5 describes a procedure for preparing a catalyst system using the compounds of the invention, that is then used in the preparation of polyethylene; Example 6 describes preparation of LLDPE using a catalyst of the invention; and Example 7 describes preparation of isotactic polypropylene using a catalyst of the invention.